In the general practice of forming fibrous web materials, such as laid fibrous articles, it has been common to utilize a fibrous sheet of cellulosic or other suitable absorbent material which has been fiberized in a conventional fiberizer, or other shredding or comminuting device, to form discrete fibers. In addition, particles of superabsorbent material have been mixed with the fibers. The fibers and superabsorbent particles have then been entrained in an air stream and directed to a foraminous forming surface upon which the fibers and superabsorbent particles have been deposited to form an absorbent fibrous web.
The forming surfaces utilized in such systems have been constructed with a wire or screen grid and can typically employ a pneumatic flow mechanism, such as vacuum suction apparatus, to define a differential pressure zone on the forming surface and impose a pressure differential thereon. The pressure difference has typically provided an airflow through the openings or perforations in the screen or grid of the forming surface. The use of vacuum suction to draw the air-entrained fiber stream onto the forming surfae, and pass the airflow through the forming surface has been employed in high-speed commercial operations.
The prior practice of forming airlaid fibrous webs has also employed various mechanisms to produce gradations in basis weight along the fibrous webs. For example, the mechanisms have been employed produce gradations of basis weight along a longitudinal direction of the formed web, i.e., in the direction of movement of the fibrous web through the forming process. Conventional mechanisms have also been employed for providing basis weight variations along a transverse, cross-direction of the formed web.
Conventional vacuum-deposition systems, such as those described above, have continued to exhibit various shortcomings. For example, with the conventional devices, it has been difficult to maintain a well mixed, superabsorbent distribution in narrow regions of the fibrous web. The conventional systems can excessively funnel the superabsorbent particles toward the cross-directional center of the forming surface. The conventional techniques have also produced an excessively non-uniform distribution of basis weight of fibrous material along the cross-direction in the narrow regions of the fibrous web. Additionally, the conventional techniques have not provided a sufficiently convenient method or apparatus for changing the dimensions of the formed fibrous web. Where the formed fibrous web includes an interconnected plurality of web segments, it has been difficult to adjust the dimensions of the desired web segments without a significant reconstruction of the forming surface. Changes to the dimensions of the formed fibrous web have required the procurement, storage and maintenance of multiple sets of forming screens and introduced excessive downtime and change over costs. Accordingly, it would be a substantial advance in the art to provide a method and apparatus which can provide a more efficient removal of the formed web from the forming surface, and can better provide an adjusting of the dimensions of the intended web segments to more efficiently form components for articles of various, different sizes.